1978 Gottlieb system one Dragon sound problem, Only one sound comes from the speaker and it is steady . i replaced the sound board and the same issue exist. the edge board connectors are good,, i followed the wiring to the next connector "Molex" and pulled the green/red wire "100s "sound and the sound stops, pulling out the 10s or the 1000s wires the sound continues.

IMG_0214 (resized).JPG

I checked all four transistors and you are correct! the far right transistor" knocker" is failed, the other three test good using a digital multi-meter on diode mode. I will acquire a new transistor and replace the failed one and then report back here as to what i find on solving the sound PROBLEM. Phil,,,,,,,,, attached is photo of where these are on the board box for reference

IMG_0313 (resized).JPG

IMG_0314 (resized).JPG

After replacing the transistor NTE part# 261 and the associated diode NTE # 519 on the driver board,,. {which are the parts for the Knocker} I put the board back in and checked all edge board connectors.. I still have the same problem with the sound being constant,, no beep or bop sound. as i posted originally a new sound board is in place. anyone got a idea where to go next...???????. attached photos are of the diode i installed "far left one.. and the transistor far right in the other photo

IMG_0326 (resized).JPG

IMG_0331 (resized).JPG

Let me also add that the knocker coil is not attached to the system, it had burned/stuck long ago and i simply removed it and capped off the two wires. The transistor and diode failed most likely due to the stuck knocker coil. Thank you, Phil

Hello, i had to order the sn7417n... i wanted to know should i test all the resistors associated with it ? i would have to unsolder one leg of each to test thanks Phil

ok that makes sense to desolder the z6 "intergrated circut",,,,,,then the associated resistors can be checked at that time since they wont be associated with the IC..... I noticed that the "out hole" is part of that Z6 circuitry, maybe this will also cure the problem i have at the outhole. When a game starts the ball kicks out to the shooter, but after the ball goes out of play it does not auto kick out to the shooter, i have a push button inline with the Blue/Red wire to solenoid and that is how i have been getting the ball to kick out to shooter.

Thank you Inko! I am happy to report that replacing the IC that you mentioned Z6 on the MPU = main control board. its the one to the left in the photo above the A1-J5 board connector.. HOw wonderfull i now have sound, and the out hole delivers the ball as it should and the right vari-target now sets and resets as it should , Thank you out there in the Netherlands my friend.. I have several of the Ics left SN7417n.... If anyone needs one let me know... there is alot going on in that one IC that i replaced.. Phil Indpls Indiana

IMG_0347 (resized).JPG

Inko, i started a new topic on my high score issue which developed after doing the above repairs. basically its not recording the high score just the most recent one.. i made a new topic just so others will see it too.